Plastics are undeniably useful materials that have found their way into virtually all human activities. However, with yearly global plastic production exceeding 400 million tons, the environmental threat posed by increased plastic consumption and disposal, contributing to its pollution, is also bigger than ever. Considering that only one-tenth of all plastic waste is recycled, new technologies that can help tackle this growing problem are urgently required.
Catalytic recycling techniques, such as hydrogenolysis and hydrocracking, are emerging chemical processes that can break down plastic waste into simpler components using catalysts. Traditional recycling involves melting and remolding plastics into lower-quality materials, whereas catalytic recycling can convert plastics into valuable chemicals and fuels, enabling a more sustainable and efficient reuse. Though certainly promising, catalytic recycling methods need further refinements before they are ready for adoption on an industrial scale.
In a recent study published in Nature Communications online on 29 November, 2024, a research team led by Professor Insoo Ro of Seoul National University of Science and Technology, Korea, recently made a breakthrough discovery in the catalytic recycling of polyolefins, which comprise 55% of global plastic waste. As explained in their article, the researchers revealed the surprising benefits of adding water during polyolefin depolymerization when using ruthenium (Ru)-based catalysts.
After synthesizing and experimenting on various Ru-based catalysts on different supports, the team found that catalysts with both metal and acid sites exhibit dramatically improved conversion rates when water is added to the reaction mixture. “The addition of water alters the reaction mechanisms, promoting pathways that enhance catalytic activity while suppressing coke formation,” explains Dr. Ro, “This dual role improves process efficiency, extends catalyst lifespan, and reduces operational costs.”
The researchers investigated the reaction mechanisms in detail, shedding light on the effect of Ru content and the proximity and balance between metal and acid sites. Under optimal conditions, Ru/zeolite-Y catalysts showcased a 96.9% conversion rate for polyolefins.
Finally, to explore the viability of this type of catalytic recycling, the team conducted a techno-economic analysis and a life cycle assessment of the proposed approach. The results clearly underscored the potential of implementing a real commercial-scale process using Ru/zeolite-Y catalyst. “The addition of water not only enhances carbon efficiency, it improves economic and environmental performance, also increases the conversion of polyolefins to valuable fuels like gasoline and diesel,” highlights Dr. Ro. Adding further, he says, “This approach thus represents a viable alternative to conventional waste management practices and offers a solution to reduce landfill and ocean pollution caused by polyolefins—the largest contributor to plastic waste.”
Overall, this breakthrough in catalytic depolymerization could revolutionize how we deal with plastic pollution and help us efficiently deal with this serious environmental threat. The research team has high hopes that this technology will evolve over the next few years to the point that mixed plastic waste can be processed without pre-sorting, making recycling efforts more cost-effective and simpler to implement. “By demonstrating a sustainable and economic approach to transforming plastic waste into valuable resources, our research could help drive policy changes, inspire investment in advanced recycling infrastructure, and foster international collaborations to address the global plastic waste crisis. Over time, these advancements promise cleaner environments, reduced pollution, and a more sustainable future,” concludes Dr. Ro on an optimistic note.
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Reference
DOI: 10.1038/s41467-024-54495-5
About the institute Seoul National University of Science and Technology (SEOULTECH)
Seoul National University of Science and Technology, commonly known as 'SEOULTECH,' is a national university located in Nowon-gu, Seoul, South Korea. Founded in April 1910, around the time of the establishment of the Republic of Korea, SEOULTECH has grown into a large and comprehensive university with a campus size of 504,922 m2. It comprises 10 undergraduate schools, 35 departments, 6 graduate schools, and has an enrollment of approximately 14,595 students.
Website: https://en.seoultech.ac.kr/
About the author
Professor Insoo Ro earned his B.S. degree magna cum laude in Chemical Engineering from Rice University, USA, in 2012 and his Ph.D. from the University of Wisconsin-Madison, USA, in 2017 under Professor James Dumesic and Prof. George Huber. After conducting postdoctoral research at UC Santa Barbara, USA, with Prof. Phillip Christopher, he joined Seoul National University of Science and Technology, Korea, in 2020 as an Assistant Professor. He has published over 30 papers in various prestigious journals, including Nature and Nature Communications, and has received numerous awards, such as the Miwon Young Scientist Award and the Science & Technology Outstanding Paper Award.
Journal
Nature Communications
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Unraveling the role of water in mechanism changes for economically viable catalytic plastic upcycling
Article Publication Date
29-Nov-2024
COI Statement
The authors declare that they have no competing interests.